Tree-Ring Dating of Alpine Fault Earthquakes, New Zealand

最近新西兰地震的树轮测年是地震引起的区域岩崩事件地衣测年的重要而可靠的测试。地衣研究表明，距离最近的阿尔卑斯断层地震已经过去了240年，一场8.1 +0.2级的地震可能很快就会使阿尔卑斯断层破裂约400公里。地衣测量地震日期的验证将证实建立地震监测和减少地震危害计划的需要。小片的相同年龄的树木是典型的热带雨林之间的高山断层和海岸在新西兰的南韦斯特兰地区。风暴或地震等扰动事件对森林树冠的部分破坏，使新一代的木（Dacrydium cupressinum）得以发芽并填补空隙。在我们将进行研究的海岸附近的Okarito森林，在排水不良（地震敏感）的土壤上，再生斑块似乎更大。Boyd Cornere在一个更内陆的地点的两个地块上对均匀年龄的rimu斑块的发芽时间进行了增量核估计。他的硕士论文表明，这两个地块在大约250年前都有过树冠打开的干扰。这些初步结果鼓励我们通过研究树轮宽度突变增减的时间来准确地确定森林扰动事件的年代。提出的树木年代学数据集是在Okarito持续产量森林中选择性采伐的副产品。我们工作的初始阶段将是开发树木种群年龄的空间模式模型。这项重要的任务将使我们能够预测地震震动对树木年轮宽度的影响。1993年和1994年将采伐大约1000棵成熟的林木。树木年轮宽度和密度的异常模式将确定与标准年轮的偏离。我们将选择、准备和分析200-300个来自基缘树干的剖面，以确定冠层打开事件、树木损害事件和发芽日期。1年级——Okarito森林林分动态研究；样品收集、运输和准备；树木年轮的测量和交叉定年。二年级——研究树木年轮异常，分析数据，准备报告。我们的项目具有多学科意义。比较树木年轮和地衣测定的年代，可以验证一种比放射性碳测年更准确的新的地表暴露测年方法。我们期望确定邻近的阿尔卑斯断层库克和布鲁纳段的地震复发间隔，以及最近一次地震以来的时间。这将检验大地震即将来临的假设。生态方面的最终成果将是增进对森林动态和微环境以及森林-地貌关系的了解。

9316428 Bull Tree-ring dating of recent New Zealand earthquakes is an important and robust test of lichenometric dating of regional rockfall events caused by earthquakes. Lichen studies indicate that about 240 years have elapsed since the most recent Alpine fault earthquake, and a magnitude 8.1 +0.2 earthquake may soon rupture about 400 km of the Alpine fault. Verification of lichenometry earthquake dates would substantiate needs for establishing seismic monitoring and earthquake hazard reduction programs. Small patches of trees of the same age are typical of the rain forest between the Alpine fault and the seacoast in the South Westland district of New Zealand. Partial destruction of the forest canopy by disturbance events, such as windstorms or earthquakes, allows a new generation of rimu (Dacrydium cupressinum) to germinate and fill the gaps. Regeneration patches appear to be larger on poorly drained (seismically sensitive) soils of the Okarito Forest near the coast where we will make our study. Increment-core estimates of germination times for even-age patches of rimu in two plots at a more inland site were made by Boyd Cornere. His M.Sc. thesis suggests that both plots had a canopy- opening disturbance approximately 250 years ago. These preliminary results encourage us to accurately date forest-disturbance events through study of times of abrupt increase or decrease of tree-ring widths. The proposed dendrochronology data set is a by-product of selective logging in the Okarito sustained-yield forest. An initial phase of our work will be to develop a model for spatial patterns of tree populations ages. This important task will allow us to make predictions about the way seismic shaking will affect tree-ring width. About 1000 mature rimu trees will be harvested in 1993 and 1994. Departures from a standard chronology for rimu will be identified by anomalous patterns of tree-ring widths and densities. We will select, prepare, and analyz e 200-300 sections from basal rimu trunks for dates of canopy-opening events, tree- damage events, and germination dates. Year 1--Stand dynamics study of the Okarito Forest; sample collection, shipping, and preparation; measuring and cross-dating of tree rings. Year 2-- studies and dating of tree-ring anomalies, analysis of data, and report preparation. Our project has multidisciplinary significance. Comparison of tree-ring and lichenometric dates should validate a new surface- exposure dating method that is more accurate than radiocarbon dating. We expect to determine the earthquake recurrence intervals for the adjacent Cook and Brunner segments of the Alpine fault, and the times since the most recent earthquakes. This will test the hypothesis that a major earthquake is imminent. An ecological end product will be improved understanding of forest dynamics and microenvironments, and forest-landforms relations.